Hesperidin, conventionally known as vitamin P, is a glycoside of hesperetin, and a flavonoid compound that is contained in large amounts in oranges, lemons and other citrus fruits, and particularly in the rind of unripe fruit. Hesperidin is found in abundance in nature, and even though it possesses physiological activity such as antiallergic action, antiviral action and capillary reinforcing action, the range of its utilization has been limited. For example, since it is difficult for hesperidin to be absorbed by the body, the resulting antioxidative effects are extremely low, thereby preventing it from being used as an antioxidant. It is therefore expected that hesperidin will be used more effectively in the future.